76 ANNUAL REPORTS OF DEPARTMEN1 OF AGRICULTURE, I 
Research findings applied to eradication of phony peach 
Annual roguing of peach trees Infected with the phony peach 
ease in ;i single orchard will do! eliminate the disease or appreciably 
reduce it in areas of serious infection and rapid natural spread, 
tudiee have shown. Only when roguing is practiced in all 
orchards in an area is the disease sufficiently inhibited to allow prof- 
itable operatioi 3. A.rea-wide roguing materially delay- infection in 
new plantings. If the i develops unchecked, the number of 
infected trees increases bo rapidly thai orchard plantings an 
Longer profitable. 
S a.kdng cut seel ions of wood from the tops of peach t rees in acidu- 
lated methanol may give the same evidence of the presence <d' phony 
peach disease virus as when this test is applied to sections of the root. 
Plant pathologists perfected the root-section test many year- _ . 
When phony peach virus is present, the cut section -how- purplish 
spots in the wood. Trials of the top-wood method with trees used in 
insect-transmission tests indicate that phony peach in small trees may 
be diagnosed in as short a period as 6 months, in com rast to the 2 or 3 
year- required when diagnosis is based on the development of visual 
symptoms in infected trees. It' studies now in progress continue to 
.-how that the chemical test is dependable, the studies of the trans- 
mission of this disease by insects can be greatly accelerated. There 
will also be a great saving in greenhouse spaa — an expensive item in 
the research program dealing with insect transmission of the disease. 
The-.- tests are being carried on in cooperation with the Bureau of 
Plant Indu-try. Soil-, and Agricultural Engineering. 
Using the new diagnostic technique, a preliminary survey for the 
presence of phony peach in wild plum was made. Plum- appear to 
tolerate the disease while masking visual symptoms. The limited 
sampling of the preliminary work showed that the disease occurs in 
wild plum in widely scattered Localities in the infected State-. 
Infected States revised their phony peach disease quarantines 
conform to the new developments and to the previously announced 
findings that leafhoppers are vectors of the disease. 
Phony peach infections were found on 1,051 properties in 65 coun- 
cil g the calendar year L950. More than 57,000 tret'- showed 
3e symptoms. There was a marked reduct ion from the 1949 inci- 
dence of the disease in A l,i ha ma. Arkansas, Louisiana, Missouri, South 
Carolina, and Texas. There was uo significant change in Georgia, 
Mississippi, and Tennessee. Lowndes County, Miss., Shelby County, 
Tenm. and Kerr and Upshur Counties, Te\.. were found tree from 
infection and weie removed from >tati' quarantine. 
An all-time low in peach mosaic was disclosed by inspectors during 
the calendar year I960. This reduction was general except in south- 
tern Arkansas, v, firs! comprehensive survey in that area 
showed an Increase. More than t,400 trees on 970 propel ties scattered 
in L6 count i< i States were found infected. 
